Sericulture Questions in English

(D) The silkworm is the larva or caterpillar of the silk moth, $Bombyx \text{ mori}$. It is an economically important insect that produces silk. In its life cycle, the adult stage is a moth, while the larval stage is commonly referred to as a silkworm.

(C) In insects,the juvenile hormone $(JH)$ is responsible for maintaining the larval stage and preventing premature metamorphosis into the pupal or adult stages.
During the larval development,high levels of juvenile hormone are present.
As the larva reaches its final stage,the level of juvenile hormone decreases.
If the juvenile hormone is absent or its concentration drops significantly,the larva undergoes metamorphosis and transforms into a pupa.
Therefore,the absence of juvenile hormone triggers the transition from the larval stage to the pupal stage.

(D) Sericulture is the commercial rearing of silkworms for the production of silk.
In India,various species of silkworms are reared for different types of silk.
$1$. $Bombyx mori$ (Mulberry silkworm) is the most common species used for mulberry silk production.
$2$. $Antheraea paphia$ (Tasar silkworm) is a wild silkworm species found in India.
$3$. $Attacus ricini$ (Eri silkworm) is also reared in India.
Since all these species are found and utilized in India for sericulture,the correct answer is $D$.

(A) Commercial silk is obtained from the $Cocoon$ stage of the silkworm $(Bombyx \text{ } mori)$.
The larva (caterpillar) spins a protective case around itself made of silk fibers, which is known as the cocoon.
In the sericulture industry, the cocoons are harvested and processed to extract the long, continuous silk filaments before the adult moth emerges and damages the fibers.

(A) The rearing of silkworms for the production of silk is known as $Sericulture$.
$Pisciculture$ refers to the breeding and rearing of fish.
$Apiculture$ is the maintenance of beehives for the production of honey.
$Horticulture$ is the branch of agriculture that deals with the art,science,technology,and business of growing plants.

(B) Silk is produced by the silkworm $(Bombyx \text{ } mori)$ during its pupal stage. The larva spins a protective covering around itself known as the cocoon, which is composed of long, continuous protein fibers called fibroin. Commercial silk is obtained by unwinding these cocoons.

(D) Flacherie is a serious disease in silkworms caused by viruses. It is characterized by the softening of the body and the presence of a foul-smelling fluid. Pebrine is caused by a protozoan $(Nosema \ bombycis)$,while Muscardine is a fungal disease.

(B) Karnataka is the largest producer of silk in India. It accounts for a significant portion of the country's total mulberry silk production due to favorable climatic conditions and the widespread practice of sericulture.

(A) The life cycle of a silkworm ($Bombyx$ $mori$) consists of four stages: egg,larva (caterpillar),pupa (cocoon),and adult (moth).
Silk is produced by the silkworm during its larval stage to form a protective covering called a cocoon.
In the commercial production of silk (sericulture),the cocoons are harvested during the pupal stage before the adult moth emerges,as the emergence of the moth would break the continuous silk fiber.

(C) The silk produced by the silkworm $(Bombyx \ mori)$ is a proteinaceous secretion.
This secretion is produced by the specialized salivary glands,also known as silk glands,present in the larval stage of the silkworm.
As the larva prepares to pupate,it secretes this liquid protein through a spinneret,which solidifies upon contact with air to form the silk fiber.
Therefore,the correct answer is the salivary glands of the larva.

(C) Pebrine is a serious disease that affects silkworms $(Bombyx \ mori)$.
It is caused by a protozoan parasite known as $Nosema \ bombycis$.
This disease is transmitted through the eggs of the infected moth or through contaminated food.
Therefore,the correct option is $C$.

(A) $Sericulture$ is the commercial rearing of silkworms,specifically $Bombyx mori$,for the production of silk. It involves the cultivation of mulberry plants to feed the silkworms,followed by the harvesting of cocoons to extract silk fibers.

(C) Silk fiber is primarily composed of two proteins: Fibroin and Sericin.
Fibroin is the structural protein that forms the core of the silk thread,accounting for approximately $75-85 \%$ of the total composition.
Sericin is the sticky,gum-like protein that coats the fibroin fibers,holding them together,and it accounts for approximately $15-25 \%$ of the silk thread.
Therefore,the correct composition is Fibroin $75-85 \%$ and Sericin $15-25 \%$.

(B) Mulberry leaves are the primary food source for the larvae of the silkworm,$Bombyx \ mori$.
Sericulture is the commercial rearing of silkworms for the production of silk.
Therefore,mulberry leaves are essential for sericulture.

(B) Sericulture is the commercial rearing of silkworms for the production of silk.
$Bombyx mori$ is the scientific name of the domesticated silkworm,which is the primary species used in sericulture.
$Apis indica$ is a species of honey bee used in apiculture.
$Hisardale$ is a breed of sheep developed by crossing Bikaneri ewes and Marino rams.
$Mule$ is a hybrid animal produced by crossing a male donkey and a female horse.

(B) Mulberry silk is considered the best quality silk because it is produced by the larvae of the silkworm $Bombyx$ $mori$,which feeds exclusively on the leaves of the mulberry plant ($Morus$ $alba$).
It is known for its superior texture,high luster,strength,and durability compared to other types of silk like Eri or Tasar.

(D) The Central Silk Research and Training Institute $(CSRTI)$ is a premier research institute under the Central Silk Board,Ministry of Textiles,Government of India. It is located in Mysore,Karnataka. The institute focuses on research and development in sericulture to improve silk production quality and quantity.

(A) Karnataka is the largest producer of silk in India. It contributes significantly to the total mulberry silk production of the country. Sericulture,the practice of rearing silkworms for the production of silk,is a major agricultural industry in this state.

(C) The life cycle of a silk moth $(Bombyx \text{ } mori)$ consists of four stages: egg, larva, pupa, and adult.
The larval stage of the silk moth is specifically known as a caterpillar or silkworm.
This stage is the primary feeding stage where the larva consumes mulberry leaves to accumulate energy for the subsequent pupal stage.
Therefore, the correct option is $C$.

$(A)$ The silk fibre is produced by the silkworm $(Bombyx \; mori)$ to form its cocoon.
During the pupal stage, the larva spins a continuous thread of silk around itself.
The length of this single, continuous silk filament extracted from a single cocoon typically ranges from $800$ to $1200$ yards ($\approx. 700$ to $1100$ metres).
Therefore, the correct option is $A$.

(C) Pebrine is a serious disease of silkworms caused by the microsporidian parasite $Nosema \ bombycis$. It is transmitted through the eggs of infected moths or through contaminated food.

(B) Multivoltine silkworms are breeds that produce multiple generations in a single year,often yielding up to $8$ crops annually. These are commonly found in regions like Bengal and Karnataka. While they are highly productive in terms of frequency,their individual cocoons are generally smaller and contain a lower quantity of silk compared to univoltine or bivoltine varieties. Therefore,both the Assertion and the Reason are correct,but the Reason does not explain why they produce multiple crops per year.

(A) Sericin is a natural protein produced by the silkworm $Bombyx$ $mori$ that acts as a glue to hold the fibroin filaments together in the silk cocoon.
During the process of silk reeling,sericin is often removed (degumming) to improve the luster and softness of the silk.
However,in some specific manufacturing processes,sericin is retained until the yarn or fabric stage to provide protection to the delicate silk fibers against mechanical stress and friction during weaving or processing.
Therefore,both the Assertion and the Reason are correct,and the Reason provides a valid explanation for why sericin is sometimes retained.

(A) Silk fiber is primarily composed of two proteins: fibroin and sericin. The core of the silk thread consists of the structural protein known as $Fibroin$,which provides strength and elasticity to the silk. Other proteins like $Keratin$ are found in hair and skin,$Albumin$ is found in egg and blood plasma,and $Globulin$ is found in blood plasma. Therefore,the correct answer is $Fibroin$.

(B) The fully grown caterpillar larva of $Bombyx$ $mori$ stops feeding and develops salivary glands,then it undergoes pupation.
In this stage,the larva secretes a sticky fluid through a narrow pore situated on the hypopharynx.
This secreted fluid,when it comes in contact with air,takes the form of a long thread of silk and is wrapped around the body of the caterpillar in the form of a covering called a cocoon.
The silk threads are then removed from the cocoon after killing the pupa inside.
Therefore,silk is secreted by the caterpillar larva of the silkworm.